heart rate monitor is it worth it?

You would log them manually...you would have to go in and pick the activity or create an exercise and log your calories. A good HRM is reasonably accurate for an aerobic event, but still an estimate. The further away you get from a steady state aerobic event, the less accurate it is for calorie burn.

I like mine for the sole purpose of monitoring my HR and working in and through various zones depending on my particular session and what I'm trying to accomplish. I could probably do it by feel at this point, but I like seeing the read out on my watch....plus, sometimes I'm out on a ride and I get distracted by the scenery and inadvertently slow down...I have my HRM set to beep at me if I go below 130 BPM on a long ride.

I LOVE my HRM. I don't count on the calorie burn as gospel, but it's a really good indicator for me of how intense my workouts are. During a workout, I watch my heart-rate, not the calories burned, and I get a good idea of whether I need to take it up or down a notch. Even if the calorie burn is off, it's off for everything at the same rate, so when I try a new workout, I can still estimate intensity in comparison to my normal routine. I do a lot of classes at the gym and sometimes I find myself plodding along, I take a look at my HRM and see that my heart rate is only like 120 so I know I need to work harder.

I tried a Timex HRM and it way over-estimated my calorie burn and operation was tedious. Got a Polar instead and I feel it's much more accurate and easier to operate.

I have the Polar FT40 I love it!